自六十年代雷射發現開始，透過材料的非線性特性，大量的應用:如頻率轉換，寬頻光梳等已被利用在日常生活與各式科技所需的系統與元件中。本論文中，我們利用Z掃描(Z-scan)量測出由PECVD成長的石墨烯、及由濺鍍成長的五氧化二鉭薄膜的光學非線性特性。
在第一部分我們量測了由PECVD成長的石墨烯的飽和吸收係數，其調製深度α0為〖4.2×10〗^8 (m^(-1))，飽和強度分別為4.2x108 (m-1)與2.5x107 (Wm-2)。 另外，我們也量測了其在不同能量下的能量相依性及波長760-840nm下的波長相依性。入射光強從0.28-1.5(GWcm-2)，其非線性折射率值從5.5×10-8(cm2W-1)到1.07×10-8 (cm2W-1)，隨著能量增加，非線性折射率降低；而其非線性折射率隨著波長的增加而降低。由PECVD成長之石墨烯的非線性折射率和其他方法長成之石墨烯相近。利用Open aperture Z-scan對其雙光子吸收係數作量測，從波長750nm到840nm，其雙光子吸收係數從1.32×〖10〗^(-5)(mW-1)降至0.85×〖10〗^(-5)(mW-1)。然而，由PECVD成長的石墨烯，其雙光子吸收係數和其他方法長成之不同層數的石墨烯大了好幾個數量級，這也使得其成為具有潛力的雙光子吸收元件的材料。
在第二部分，我們利用濺鍍成長了五氧化二鉭薄膜，如同n&k量測一般，利用Z掃描的開孔(Open aperture)實驗及閉孔(Close aperture)實驗的穿透率比較發現五氧化二鉭在800nm下吸收現象不顯著；但在非線性折射率方面，我們量測了在不同退火時數下的五氧化二鉭薄膜，針對光學特性最佳之退火3小時的五氧化二鉭薄膜，我們討論了在波長800nm下的能量相依性：入射光強度從0.7-4.8(GWcm-2)，其非線性折射率從1.37×10-11(cm2W-1)到0.16×10-11(cm2W-1)，其非線性折射率隨著能量上升而降低。從低吸收與高非線性係數，我們討論了它在非線性應用未來的潛力。

To optimize the performance, such as frequency conversion, material or devices modulation and so on, nonlinear nature of material has been applied accompanying with the development of laser. As a result, the optical nonlinearity, for example: nonlinear refractivity, saturation flurence.. , are very important. In this thesis, using femtosecond Z-scan technique, the nonlinearities of Plasma-enhanced chemical vapor deposition (PECVD) growth graphene and sputter growth Tantalum pentoxide (Ta2O5) were investigated.
First, the nonlinear absorption coefficient of PECVD growth Graphene was characterized. The modulation depth of 4.2x108 (m-1) and saturation flurence of 2.5x107 (Wm-2) were obtained. Additionally, the two photon absorption (TPA) coefficient b as high as 10-5 (m/W) was observed. The wavelength dependence and possible mechanism of tremendously large TPA coefficient were discussed as well.
Second, the nonlinear properties of Ta2O5, which is a potential material for nonlinear waveguide, were studied by Z-scan. The nonlinear refractive around 10-12 (cm2W-1) was extracted from Z-scan profile. Compared to conventional materials for nonlinear waveguide, Ta2O5 exhibits the feasibility for nonlinear devices. Furthermore, the nature of low loss shows the potential for the ultrabroad band frequency comb and optical computing.

第一章 緒論........................................................6
第二章 非線性光學量測方法及研究....................................8
2-1非線性光學介紹..................................................8
2-2自相位調變(Self phase modulation)...............................11
2-3簡併四波混頻(Degenerate four wave mixing).......................14
2-4非線性干涉儀(Nonlinear interferometry)..........................16
2-5近三波混頻(Nearly degenerate three-wave mixing).................17
2-6 Z掃描(Z-scan)..................................................19
2-7 總結...........................................................25
第三章 PECVD 成長之石墨烯之非線性光學量測及研究....................26
3-1 石墨烯介紹(Introduction of graphene)............................26
3-2利用Z掃描對PECVD長成之石墨烯之雙光子吸收之研究(PECVD graphene two photon absorption investigation by Z-scan)..........................32
3-2-1 實驗架設及測試.......................................32
3-2-2 光斑(Beam size)大小量測..............................33
3-2-3 脈衝雷射峰值能量計算.................................35
3-2-4 飽和吸收量測結果.....................................36
3-2-5 Open aperture Z掃描(Z-scan)量測PECVD長成之石墨烯的雙光子吸收.....................................................37
3-3 利用Z掃描對PECVD長成之石墨烯之非線性折射率研究...............43
3-3-1 PECVD長成之石墨烯的非線性折射率能量相依性............43
PECVD長成之石墨烯的非線性折射率波長相依性...........47
3-4 結論...........................................................54
第四章 五氧化二鉭(Tantalum pentoxide-〖Ta〗_2 O_5)之非線性光學量測及研究.................................................................55
4-1 五氧化二鉭(Ta_2 O_5)介紹..........................................55
4-2 Ta_2 O_5薄膜製造及其特性..........................................57
4-2-1 Ta_2 O_5薄膜製備........................................57
4-2-2 Ta_2 O_5薄膜特性研究....................................59
4-3 Ta_2 O_5薄膜在不同退火時數下之非線性分析..........................62
4-3-1 系統架設.............................................62
4-3-2 光斑大小量測.........................................62
4-3-3 Z-scan量測結果.......................................63
4-4 Ta_2 O_5薄膜在退火時數3小時下之非線性分析........................67
4-4-1 系統架設.............................................67
4-4-2 退火3小時之Ta_2 O_5薄膜的非線性折射率能量相依性........67
4-5 結論...........................................................72
第五章 結論與未來展望..............................................73
Reference..........................................................75

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